Declare @lDateFrom As DateTime = N'2014-11-10T08:05:25.1'
Declare @lDateTo As DateTime = N'2014-11-12'
Declare @lTmpDate As DateTime

Declare @lFirstHour As TinyInt = 6
Declare @lShiftLength As TinyInt = 12

Declare @lDateFromZeroTime As DateTime
SELECT @lDateFromZeroTime = DATEADD(dd, 0, DATEDIFF(dd, 0, @lDateFrom))

Declare @lDateToZeroTime As DateTime
SELECT @lDateToZeroTime = DATEADD(dd, 0, DATEDIFF(dd, 0, @lDateTo))

Declare @lShiftDates Table
	(
		[start_date] DateTime,
		[end_date] DateTime
	)

Set @lTmpDate = @lDateFromZeroTime

While (@lTmpDate <= @lDateToZeroTime) Begin
	Insert Into @lShiftDates ([start_date], [end_date]) Values (DateAdd(hh, @lFirstHour, @lTmpDate), DateAdd(hh, @lShiftLength, DateAdd(hh, @lFirstHour, @lTmpDate)))
	Set @lTmpDate = DateAdd(dd, 1, @lTmpDate)
End

Select * From @lShiftDates